docs: def get_colname(self, colnum):
          """
          Get the name associated with the given column number
  
          parameters
          ----------
          colnum: integer
              The number for the column, zero offset
          """
          if colnum < 0 or colnum > (len(self._colnames)-1):
              raise ValueError(
                  "colnum out of range [0,%s-1]" % (0, len(self._colnames)))
          return self._colnames[colnum]